Rotary Encoder Slit Position Error Compensation
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Solution Overview
Problem
Conventional rotary encoders face challenges in accurately detecting rotation angles and revolutions per minute due to positional errors in slits caused by manufacturing inaccuracies and environmental factors like temperature and humidity, leading to unreliable angle detection.
Innovation Solution
A control method for rotary encoders that calculates the actual angle of each slit by determining the difference between assumed and actual angles, resets the count value of a second slit with an actual angle closest to the first slit's assumed angle to minimize angular error, and uses a lookup table to adjust the count values, thereby reducing positional errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional manufacturing processes are used to form slits on the disc, then manufacturing simplicity is maintained, but manufacturing precision deteriorates due to high probability of forming slits at unintentional positions
Solution Approach 1:
The patent applies preliminary action by measuring and storing the actual positions of all slits during an initial calibration phase. These measured positions are saved in a lookup table that is used during normal operation to compensate for positional deviations. This preliminary measurement and storage action enables the system to achieve high manufacturing precision without requiring complex real-time adjustment mechanisms.
2Manufacturing precision
If the disc is subjected to temperature or humidity changes during storage, then environmental adaptability is tested, but manufacturing precision deteriorates as slit positions become distorted
Solution Approach 1:
The patent implements feedback by continuously comparing the assumed position of each slit with its actual measured position stored in the lookup table. During operation, the system uses the pre-stored actual position data to correct for deviations caused by temperature and humidity changes. This feedback mechanism allows the encoder to maintain manufacturing precision despite environmental factors that would otherwise cause slit position distortion.
3Measurement precision
If the control unit assumes specific rotation angles for each slit, then operational simplicity is maintained, but measurement precision deteriorates when actual slit positions differ from assumed positions
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the actual rotation angles corresponding to each slit position during an initial calibration phase. These pre-computed angle values are saved in a lookup table, eliminating the need for complex real-time angle calculations during normal operation. This preliminary computation enables high measurement precision while maintaining operational simplicity through direct table lookup.
4Measurement precision
If slit positions are distorted due to manufacturing or environmental factors, then reliability of the encoder structure is maintained, but measurement precision deteriorates as detection accuracy decreases
Solution Approach 1:
The patent implements feedback by using pre-measured actual slit positions to continuously correct rotation angle measurements. The system compares the detected slit position with the stored actual position data and applies corrections based on the difference. This feedback mechanism ensures that even when slit positions are distorted due to manufacturing tolerances or environmental factors, the measurement precision and detection reliability are maintained through real-time compensation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enhances the reliability of rotation angle detection by compensating for and reducing angular errors between assumed and actual slit positions, ensuring accurate measurement even under conditions of slit distortion.
Implementation Method 1
an optical sensor, which emits light to the plurality of slits and receives the light transmitted through the plurality of slits
Data Source
AI summary
The control method includes obtaining an assumed angle and an actual angle of each of the plurality of rotation angle detecting members, determining a first rotation angle detecting member, the assumed angle and the actual angle of which differ from each other, determining a second rotation angle detecting member having the actual angle closest to the assumed angle of the first rotation angle detecting member, resetting the given count value of the second rotation angle detecting member to a new count value of the first rotation angle detecting member, changing the actual angle of the first rotation angle detecting member via the new count value of the first rotation angle detecting member to reduce an angular error between the assumed angle and the actual angle of the first rotation angle detecting member.